do not use system is<alpha|alnum|space|...>, because of the different implementations (and in OpenCV we assume english names of the identifiers etc)

replaced alloca() (a.k.a. cvStackAlloc) with AutoBuffer or vector() everywhere. cvStackAlloc() is still defined, but we do not need alloca() anymore to compile and run OpenCV (fixes #889 and may be some others)

replaced alloca() (a.k.a. cvStackAlloc) with AutoBuffer or vector() everywhere. cvStackAlloc() is still defined, but we do not need alloca() anymore to compile and run OpenCV (fixes #889 and may be some others)

added Mat::push_back, pop_back and related operations; enabled reading/writing/creating/copying matrices with zero dimensions.

mainly cmake stuff, but in persistance the wcstombs
is not supported on android, and in
sift.cpp there was and ifdef that affected arm and this
causes undefined symbols on android.